Stock-based Compensation Plans - Additional Information 4 (Detail) - USD ($) shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Deferred compensation plan vesting period			3 years
Deferred compensation plan	$ (12,587,000)	$ 11,142,000	$ (4,050,000)	$ 7,561,000
Shares held in rabbi trust total	6.2		6.2		3.2
Vested shares held in rabbi trust	3.8		3.8		2.7
Post-Retirement Medical Plan
Defined Benefit Plan Disclosure [Line Items]
Estimated prior service cost amortized from accumulated other comprehensive income into general and administrative expense	$ 90,000	$ 90,000	$ 185,000	$ 185,000